Excavating buckets and other excavating equipment are typically subjected to harsh conditions. A series of wear members are usually provided to protect the digging edge and other portions of the bucket from premature wear. Wear members have in the past been secured to the bucket in many different ways.
For example, in U.S. Pat. No. 4,570,365 to Bierwith, the wear members are secured to the lip of the bucket through the use of a wedge and spool lock arrangement that is fit through a hole in the lip spaced from the front edge. In this arrangement, the spool pinches the rear ends of the wear member against the inner and outer faces of the lip as the wedge is driven into the hole. However, under load, the legs of the wear member can shift and cause loosening of the lock and possible loss of the wear member. In addition, the formation of a hole in the lip weakens the lip and lessens its ability to effectively resist large loads as it is forced into the ground.
In U.S. Pat. No. 4,748,754 to Schwappach, a lateral boss is welded to the inner face of the tip as a support for holding the wear member to the lip. The wear member has a rearwardly extending leg provided with an opening into which the boss is received. A lock composed of a pair of opposed, generally C-shaped securing members joined by a central elastomer is placed in the opening between the boss and the end of the leg. The elastomer expands to fill the opening and provide some tightening of the assembly. However, the elastomer does not possess sufficient strength for the lock to well withstand the expected loads. Hence, the wear member can shift during use, which may result in ejection of the lock and loss of the wear member.
U.S. Pat. No. 5,088,214 to Jones discloses a wear assembly wherein a longitudinal boss is fixed to the lip for receipt in a corresponding slot defined in the wear member. A hole is formed in the wear member to receive and position a lock against the rear end of the boss to hold the wear member to the lip. The lock is a rigid, block-shaped member that provides firm resistance to the applied loads. While the use of a rigid member instead of an elastomeric body avoids overloading the lock during use, it does not provide any ability to tighten the mounting of the wear member on the lip.
U.S. Pat. No. 5,653,048 to Jones et al. discloses a lock with a rigid body and a threaded plug to tighten the wear member onto the lip. However, the threaded plug can loosen during use in some circumstances due to vibration and impact forces. Moreover, the lateral latch construction used in both this patent as well as the '214 patent, can at times be difficult to release on account of fines being impacted in the expansion space for the elastomer.
Accordingly, there is a need for an improved assembly for attaching a wear member to the digging edge of an excavator that avoids the problems of the prior art.